Soil water retention and maximum capillary drive from saturation to oven dryness

摘要: This paper provides an alternative method to describe the water retention curve over a range of contents from saturation oven dryness. It makes two modifications standard Brooks and Corey [1964] (B-C) description, one at each end suction range. One expression proposed by Rossi Nimmo [1994] is used in high-suction zero residual content. (This Rossi-Nimmo modification Brooks-Corey model more realistic description low contents.) Near second eliminates region where there change with no Tests on seven soil data sets, using three distinct analytical expressions for high-, medium-, low-suction ranges, show that experimental curves are well fitted this composite procedure. The contributes little maximum capillary drive, defined good approximation air system as HcM = ∫0∞krw dhc, krw relative permeability (or conductivity) hc suction, positive quantity unsaturated soils. As result, suggested does not significantly affect equivalence between van Genuchten [1980] parameters presented earlier. However, shape near “natural saturation” has significant impact value drive. estimate power law, extended will exceed obtained new procedure 25 30%. possible tell which appropriate. another set, conductivity available, support view authors measurements coupled speculative sufficient accurately determine (maximum) drive dynamic scalar, whereas static character. Only infiltration rates time can precision given soil.